Processes in the cultivation of cells have been conducted by a skilled operator manually in a clean room which is sterilized as much as possible by strict production steps. Therefore, large-scale cell cultivation requires enormous cost of manpower and considerable cost of equipment, which have been enormous obstacles to industrialization.
It is possible to automate a series of manual culture operations using a robot and to reduce the cost of manpower. However, because the culture operations include operations in which the inside of the culture vessel is opened, such as the change of the culture medium in which the cover of the culture vessel is opened, the risk of contamination from the outside cannot be eliminated. Therefore, the whole system including the robot has to be placed in a large-scale clean room, and it is difficult to reduce the cost of equipment considerably.
Accordingly, systems for culturing cells in which a closed system is formed by connecting a liquid bag containing a culture medium, a culture vessel, a liquid waste bag and the like (hereinafter referred to as a closed culture system) and in which the change of the culture medium and the like are conducted in the system have been invented. An example of the systems is described in JP-A-2011-142837 (PTL 1). Because the risk of contamination from the outside can be eliminated with such a system, keeping the cleanliness of the installation location of the system at the minimum level is sufficient, and the cost of equipment can be reduced considerably.
On the other hand, a closed culture system is restricted in the handling of liquid delivery; for example, a liquid should be sent by a liquid-driving force from the outside of the system. Therefore, the handling requires ingenuity. For example, when a liquid is sent to the culture vessel, it is necessary to send the liquid with ingenuity so that air does not remain in the culture vessel. JP-A-2009-125027 (PTL 2) describes an example in which the inlet port and the discharge port of the culture vessel are spaced and the culture vessel is inclined vertically when a liquid is sent.